The Conservative party was urged yesterday to conduct an inquiry into a hate campaign carried out by one of its former parliamentary candidates against his Liberal Democrat opponents.

Ian Oakley, 31, who was selected in the Labour-held seat of Watford in 2006, was sentenced yesterday to 18 weeks in prison, suspended for 12 months.

St Albans magistrates said his "vile and persistent" campaign, including harassment and criminal damage aimed at dozens of Lib Dem supporters and councillors, was an attempt "to pervert the democratic process". Calling for the inquiry, his principal target, Sal Brinton, the Lib Dem candidate for Watford, said the Tories locally and nationally have never apologised nor responded in any way since Oakley pleaded guilty in August.